storage/shortener.go

   1 package storage
   2
   3 import (
   4         "crypto/sha1"
   5         "encoding/hex"
   6         "path"
   7         "strings"
   8         "unicode/utf8"
   9 )
  10
  11 const MaxFilenameLen = 200
  12
  13 func PathShortener(pth string) string {
  14         parts := strings.Split(pth, "/")
  15         for i, part := range parts {
  16                 if len(part) <= MaxFilenameLen {
  17                         continue
  18                 }
  19                 n := 0
  20                 var short []rune
  21                 for (n < len(part)) && (len(string(short)) <= MaxFilenameLen) {
  22                         r, w := utf8.DecodeRuneInString(part[n:])
  23                         n += w
  24                         short = append(short, r)
  25                 }
  26                 h := sha1.Sum([]byte(part))
  27                 parts[i] = string(short[:len(short)-1]) + "-" + hex.EncodeToString(h[:])
  28         }
  29         return path.Join(parts...)
  30 }